Properties Of Samples Research Articles

Investigation of the optical and electrical properties of zinc oxide by terahertz time domain ellipsometry

In order to demonstrate the application of terahertz time-domain ellipsometry (THz-TDE) in the characterization of wide-bandgap semiconductors, we studied two zinc oxide (ZnO) single crystals with different conductivities. The optical properties of ZnO samples with low conductivity and high conductivity are both obtained by ellipsometric parameters, while the electrical properties of ZnO sample with high conductivity are well deduced and fitted using the Drude model. These results suggest that THz-TDE can effectively obtain the optical and electrical properties of wide-gap semiconductors and can be used to characterize semiconductors with carrier densities higher than 1016 cm−3.

Numerical and experimental investigation of 3D printed tunable stiffness metamaterial with real-time response using digital light processing technology

A tunable mechanical metamaterial is a type that can be altered or manipulated to change its physical properties in various situations. This study introduces a novel type of metamaterial, hydro-tunable metamaterials (HTMs), which can be dynamically adjusted in real-time by filling or draining it with water. The development of HTMs has significant implications for various fields, including mechanical engineering, biomedical applications, and energy absorption. The study involves designing and manufacturing HTMs using a Digital Light Processing (DLP) 3D printing process. The design process involves modifying an initial basic auxetic structure to create a closed and sealed structure accommodating fluid. The printed samples are then characterized using mechanical testing and finite element analysis (FEA). Experiments and simulations have found that a sample containing water behaves differently from a sample without water, resulting in an increase in stiffness. This difference can be leveraged to modify the stiffness and strength of the structure. This phenomenon is attributed to the incompressibility of water within the structure. Water exerts a hydrostatic pressure on the auxetic material, resulting in increased stiffness and resistance to compression. This technique highlights the potential of HTMs to be dynamically adjusted in real-time, leading to enhanced energy absorption and improved performance. An additional FEA was conducted to examine the impact of water pressure on the mechanical behavior of the structure. The results indicate that applying pressure or temperature to the water can significantly enhance the mechanical properties of the water-filled sample.

Study on energy consumption and failure mechanism of water-saturated coal sample during impact cracking

To uncover the mechanism of energy dissipation in coal samples when subjected to both water and dynamic load, the damage patterns and energy absorption properties of coal samples in their natural and saturated states were investigated and analyzed through Hopkinson impact experiments. The results of the study show that the mass and wave velocity of the natural coal samples show an increasing trend when they are saturated with water. And the mass and wave velocity increase by 6.35 % and 21.42 % respectively. The coal sample's level of fragmentation and dynamic strength exhibited a positive correlation with the velocity (1 m/s-5.69 m/s) of impact. When subjected to dynamic loads, both natural and water-saturated coal samples primarily undergo splitting, fracturing, and crushing. Compared with natural coal samples, saturated water coal samples show greater degree of crushing and lower mechanical strength. The dynamic strength of saturated coal sample at 5.25 m/s (15.66 MPa) decreased by 33.86 % compared with that at 5.69 m/s (23.68 MPa). The mean size of particles in coal samples, both in their natural state and when saturated with water, had an linear reduction relationship with impact speed. Conversely, the fractal dimension, which represents dissipation, had a direct relationship with impact speed. The fractal dimensions of dry and saturated coal samples are distributed in the ranges of 1.56–2.08 and 1.65–2.1, respectively. And the dissipative energy of natural coal samples between 1.09 m/s and 5.67 m/s is about 0.039 J/cm3-0.175 J/cm3, and that of saturated coal samples between 1 m/s and 5.25 m/s is about 0.034 J/cm3-0.088 J/cm3. The surface energy of coal samples was analysed and calculated, and an energy consumption prediction model was proposed to predict the energy consumption of coal samples after dynamic crushing.

Experimental Study on Mechanical Properties of Recycled Aggregate Mixed Soil.

In the context of efforts aimed at reducing carbon emissions, the utilization of recycled aggregate soil mixes for soil stabilization has garnered considerable interest. This study examines the mechanical properties of mixed soil samples, varying by dosage of a soft soil curing agent C, recycled aggregate R content, and curing duration. Mechanical evaluations were conducted using unconfined compressive strength tests (UCS), field emission scanning electron microscopy (FESEM), and laser diffraction particle size meter tests (PSD). The results indicate that the strength of the mixed soil samples first increases and then decreases with higher dosages of recycled aggregate, reaching optimal strength at a 20% dosage. Similarly, an increase in curing agent dosage enhances the strength, peaking at 20%. The maximum strength of the mixed soils is achieved at 28 days under various proportions. The introduction of the curing agent leads to the formation of a flocculent structure, as observed in FESEM, which contributes to the enhanced strength of the soil mixes. Specimens prepared with a combination of 20% R and 20% C, maintained at a constant moisture content of 20%, and cured for 28 days exhibit a balance between economic, environmental, and engineering performance.

An investigation on the wear properties of the photocurable components produced by additive manufacturing for dentistry applications: Combined influences of UV exposure time, building direction, and sliding loads

AbstractAdditive manufacturing (AM) of polymers is a highly versatile technology that can be applied to many independent sectors like automotive, aviation, medicine, and dentistry. Since it has great potential for rapid prototyping, clean‐process concepts, and the ability to produce complex shapes, the layer‐by‐layer printing method is one of the most promising alternatives for future industrial production efforts. In that sense, different from the previous studies, this work aims to elucidate the friction and wear properties of the special dental samples manufactured via photopolymerization‐based AM technology according to both for printing parameters, and dry sliding test variables. Also, this is the first initiation to examine the combined influences of the UV exposure time, building direction, and sliding force on the surface roughness, hardness, friction coefficient, wear rate, and main plastic damage mechanism of the printed samples. The results showed that the maximum average hardness value was detected as 89.8 Shore D for vertically built samples printed with 8 s exposure time. In addition, vertically printed samples exhibited better wear resistance than the horizontal samples and the rising exposure time generally affected affirmatively the hardness levels of the samples. The lowest volume loss of 78 mm3 belonged to the vertical sample at 5 N. Further, increasing test force levels caused a decrease in the friction coefficient results and triggered the volume loss increase in the samples. Among all samples, the calculated friction coefficient values changed between 0.3 and 0.87. On the other side, scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS) analyses pointed out that ascending exposure times led to the altering contact surface matchings determining the final volume loss outcomes.Highlights To obtain better surface quality, vertical printing was a useful option. Horizontally printed samples exhibited higher friction coefficients. Curing time positively impacted the wear resistance for both orientations. Grooves and debris parts were observed on surfaces with low exposure times.

Detection of adulteration in Iranian grape molasses added glucose/fructose/sugar beet syrups with 13C/12C isotope ratio analysis method.

Grape molasses (GM), produced from grapes, is a traditional Iranian food and is widely consumed in Iran. However, GM adulteration is among the most widespread illegitimate procedures involving contamination of food with foreign materials, such as adding sugar-water solution, date syrup, sugar beet syrup, and grape sauce. This study used stable carbon 13C/12C isotope ratio analysis method to detect adulteration of GM samples with glucose syrups (GS), fructose syrups (FS), and beet sugar syrups (BS) at the ratio of 0%, 10%, 30%, and 50% (by weight). Physicochemical properties of GM including °Brix, conductivity, specific gravity, pH, moisture content, ash content, hydroxymethyl furfural, sugar content, and rheological properties of samples were investigated. The δ13C isotope ratio of the GM was determined as -26.61%, that of the GS as -13.23%, that of the FS as -13.42%, and that of the BS as -16.58%. The δ13C isotope ratio increased by the addition of adulterant syrups to GM. The addition of each adulterant syrup had a different effect on the physicochemical parameters; however, the °Brix and specific gravity had a positive correlation with the δ13C isotope ratio results. The magnitudes of G' and G" increase with an increase in frequency representing the viscoelastic behavior of samples. The obtained results of this study suggest the use of δ13C isotope ratio method as a fast and accurate method to investigate the adulteration of grape molasses.

Effect of iron‐containing fillers on heat release kinetics and strength properties of polyester resin

AbstractThe influence of filling by iron‐containing fillers on the heat release kinetics and mechanical properties of industrial unsaturated polyester resin PN‐1 is investigated experimentally. The iron ore concentrate, electrostatic precipitator dust, high alumina cement grade HAC‐1, shavings made of cast iron, fine grade sand are used as fillers. To improve the strength characteristics of polyester resin composites the small amount (0.2–1.0 wt%) of organosilicon additives such as synthetic silicone rubber, tris(trimethylsiloxy) phenylsilane, octamethyl cyclotetrasiloxane are used. The heat release kinetics is studied for different ratios between accelerator (cobalt naphthenate) and initiator (cyclohexanone peroxide). The time to reach the maximum temperature of the heat release is significantly reduced when a large amount of iron ore concentrate is used as filler. The temperature of maximum heat release decreases and the time to reach it increases when adding electrostatic precipitator dust in small amount of 5 wt% to the high filled by iron ore concentrate (295 wt%) composite system. The optimum in strength indicators associated with the ratio of different fractions in systems consisting of two fillers of different properties and granulometric composition is found. The highest values of compressive strength in the cement–iron ore concentrate and sand–iron ore concentrate systems are observed. An increase in the strength characteristics of composites by 15%–20% with organosilicon additive introduction is observed. The addition of the silicone rubber increases the strength properties of samples the most among all additives considered.Highlights Effect of filling by iron‐containing fillers on the heat release kinetics and mechanical properties of polyester resin is found. The time to reach the maximum temperature of the heat release is significantly reduced when the resin is filled by a large amount of iron ore concentrate. The temperature of maximum heat release decreases when the electrostatic precipitator dust in small amount is added to the high filled by iron ore concentrate. An increase in the strength characteristics of composites by 15–20% with introduction of organosilicon additives is observed.

Synthesis of HTSP Y1<sub>1-x</sub>Fe<sub>x</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> by Sol-Gel and Solid-Phase Methods

A modified version of using of the sol-gel process at the initial stage of the synthesis of a high-temperature superconductor (HTSC) Y1-xFexBa2Cu3Oy with low Fe doping is proposed. The properties of samples obtained by sol-gel and solid-state synthesis have been compared. It has been shown that a more uniform distribution of the dopant throughout the volume of the sol-gel samples makes it possible to obtain materials with improved microstructural and performance characteristics.

Effects of surface micro-texturing laser-etching on adhesive property and failure behaviors of basalt fiber composite single-lap-joint

Laser-etching technology can perform micro-nano processing on the sub-surface of composite, thereby enhancing its mechanical interlocking to improve the adhesive performance. However, it can easily cause surface fiber damage and destroy the integrity of composite. Hence, the influences of surface micro-texturing and laser-etching effect on the adhesive property and failure behaviors of basalt fiber reinforced polymer (BFRP) composite single-lap-joint are investigated. Here, different surface micro-texturing of BFRP with different laser-etching power and line space are processed by laser-etching. The surface morphology and wetting property of experimental samples are characterized, and single lap tests are conducted to evaluate the adhesive properties. Results show that the adhesive property firstly increases and then decreases with the laser power increase, where the samples etched with 10 W and line space of 0.1 mm perform the best. It is found that the epoxy on the surface is removed by laser-etching to improve the contact area, but the fiber damage is formed to affect the adhesive property. When the laser-etching reaches a certain depth in spite of fiber damage, it can achieve the best bonding performance with the balance of performance and structural integrity. Finally, the multi-scale simulations are conducted to effectively demonstrate the laser-etched interface bonding behavior and damage evolution process of BFRP single lap joints.

Investigation of mechanical and wettability properties of commercial pure titanium by surface mechanical attrition treatment

The examination of mechanical and wettability properties of commercial pure titanium (CP-Ti) introduced a novel challenge. The microstructure of samples was analyzed by using OM and SEM micro-images. In this study, the hardness of the surface and cross section of samples was evaluated, and the effect of several surface mechanical attrition treatments (SMATed) on samples was examined. Also, the tensile test was done to compare the effect of SMAT duration on mechanical properties of samples. The contact angle method was then employed to investigate the impact of SAMT duration on the wettability trend. According to results, as the treatment time increases, twins become evident in the deeper layers of the samples. In contrast, the near-surface twins are shorter than those found in the deeper material, signifying the presence of finer grains. Moreover, the elevated hardness in SMATed samples can be attributed to several key factors, including cold work, a rise in defects and twins, and grain refinement. The surface hardness increases across the sample series (up to Ti6) due to the substantial energy input. Nevertheless, it is anticipated that further continuation of the process will result in a constant surface hardness. The increased strength observed in SMATed samples can be attributed to factors such as reduction in grain size and the formation of twins. The wettability results show that the treated surfaces exhibited a significant change in wettability compared to the untreated samples, with a 25% reduction in the contact angle. This is attributed to the surface modifications induced by the treatment process, which introduced more hydrophilic functional groups. The results also show that after 4 h of treatment, the contact angle increases, suggesting that the trend may plateau with additional treatment time.

Crystallographic orientation dependence in creep deformation of micron-thick silicon films for 3-D microstructures

In this study, the steady-state creep deformation properties of 5 μm-thick single crystal silicon (Si) films at elevated temperatures were investigated using punch creep-forming tests for the design of three-dimensional (3-D) microstructured MEMS. The relationship between the creep strain rate and stress of the Si films with {100}, {110}, and {111} planes at temperatures of 1223–1323 K was derived using finite element analysis following punch creep-forming tests, and a power-law creep constitutive equation for Si films was determined. The steady-state creep properties of the Si film samples varied clearly with crystallographic orientations. Among the three crystallographic orientations, the creep strain rate of the micron-thick Si films was the fastest for the {011} plane, followed by the {111} and {001} planes, in the applied stress range of 110 MPa to 220 MPa. This is consistent with the increasing order of magnitude of the thermal activation energy. The crystallographic orientation dependence of the steady-state creep properties of Si films is discussed based on the mobility of dislocation gliding per unit lattice and scanning electron microscope observations. The sample-size dependence of the creep strain rate of Si with the {001} plane was clearly observed between the micron- and millimeter-thick samples, which was attributed to the difference in the frequency factor of the power-law creep. However, the thermal-activation energy remained constant. This study successfully revealed the steady-state creep properties of Si films and provided useful engineering data for the design of 3-D Si-MEMS fabrication by the plastic processing of Si films.

Experimental study on dynamic mechanical properties of multidirectional constrained water-bearing coal samples under dynamic-static coupling loading

The objective of this study is to investigate the dynamic mechanical properties of coal and rock under deep water conditions. The research employs an enhanced Split Hopkinson Pressure Bar (SHPB) testing system. Five sets of dynamic impact experiments were conducted on coal samples under varying loading conditions to analyse the changes in dynamic strength, energy dissipation, fractal dimension and other characteristics of coal samples under different water content states were analyzed. The experimental results demonstrate that: (1) Under specific strain rate conditions, the dynamic strength of saturated coal samples is lower than that of natural coal samples. As the strain rate gradually increases, the bonding force generated by free water and the Stefan effect jointly act, and the peak strength of saturated coal samples under high strain rate loading conditions is higher than that of natural coal samples. (2) Under certain strain rate conditions, the absorption energy of saturated coal samples is approximately 10% to30% lower than that of natural coal samples, and deformation hysteresis phenomenon occurs in natural coal samples, thereby improving the dynamic strength of natural coal samples relative to saturated coal samples; (3) The fractal dimension of saturated coal samples with a specific strain rate under three-dimensional dynamic static combination loading is higher than that of natural coal samples, and the percentage of small particle coal samples with debris is higher than that of natural coal samples; Finally, based on the HJC model, some coal samples were selected to simulate the coal rock failure characteristics during the triaxial loading process using ANSYS/LS-DYNA, and their stress–strain curves and failure morphology diagrams were obtained. The discrepancy between the numerical simulation and the experimental results was less than 10%, thereby further elucidating and corroborating the coal failure process and dynamic mechanical characteristics.

Assessment on the influence of FDM process parameters on the mechanical properties of PLA samples

Abstract The manufacturing of functional parts from the fused deposition modeling 3D printer is limited due to poor mechanical properties, low surface finish, and huge production time. During 3D printing of prototypes, the time consumption of printing and mechanical properties of the model is directly proportional. The fused deposition modeling process parameters significantly impact the quality of printed parts. The prime objective of this research is to optimize the process parameters of a 3D printing machine (wall thickness, infill percentage, infill pattern, and infill speed) using polylactic acid material to enhance the mechanical properties with less printing time of the 3D printing model. The ultimate tensile strength and elongation of the 3D printed samples are used to evaluate the mechanical properties of the various slicing process parameters as per the standards. From the results, it is evident that the mechanical properties of the 3D printed materials increased significantly. The magnitude of ultimate tensile strength is reported as 39.972 MPa with a printing time of 28 min. From close observation, it is evident that lower infill speeds with gyroid infill pattern produce the highest ultimate tensile strength of all combinations. Also, optimal results are derived at higher wall thickness and higher infill percentage. In addition to that, finite element analysis was carried out for different infill percentages of the specimen to validate the actual result.

Study of Optical, Electrophotographic and Holographic Parameters of As-Se Condensates from the Prehistory of the Original Bulk Materials

The results of a study of the optical, electrophotographic and holographic parameters of As-Se condensates from the prehistory of the original bulk materials are presented. It has been established that the electrophotographic parameters of freshly deposited As40Se60 layers change significantly with temperature; the dependences of the maximum charging potential (U0) and the half-decay time of the potential (τ1/2) of electrophotographic As40Se60 layers in the dark on the processing temperature of the melt of the starting material are shown. The dependence of the half-life of the potential in the dark, as well as the properties of bulk samples, has an extremum in the region of Tsub~500°C. The correlation between the dependences of the properties of bulk samples and the electrophotographic parameters of the layers on Tsub indicates that the structural features of the source material in the deposition mode used affect the structure of the films.

Experimental Studies on the Siirt Herby Tulum Cheese: II. Evaluation of a New Industrial Process Model

This study was conducted to test a process that we had previously developed in parallel to the traditional Siirt Herby Cheese production method. Both raw and pasteurized Eve's milk were used parallelly in the study. Pasteurized milk was inoculated with an autochthonous starter culture which we have developed. After clot formation, breaking the clot, straining and acidification of curd by using acid whey, first pressing, adding herb and salt, and applying the second pressing stages were followed. Then, the cheese samples were packaged. No air gap was presented in the cheese containers. The entire production was completed within 24 hours. During the 120-d ripening period of the samples at 4 °C, pH was observed to be 5 and acidity was 0.7% (lactic acid). In raw milk cheese, pH was 6.8 and acidity was 1.12% at the end of the ripening period. It was determined that the method tested in this study was not recommendable for making raw milk cheese. The pasteurized milk cheese samples had at least 0.7 acidity, 5 pH, 20% fat and 20% protein; It was observed that at least 45% dry matter values could be obtained. However, the pasteurized milk cheese samples did not fully meet our expectations. The crumbling property of the cheese samples was not ideal just seen in the tradiditonal Tulum Cheeses of Türkiye. The slightly sticky and melted appearance was considered a negative property of the cheese and should be eliminated with more detailed work. Traditional production takes at least 10 d. This period may be long for industrial production. Raw milk is used in traditional production, and excessive salt is added to the cheese for hygiene purposes. Also, it is not easy to make a standard production. More research is needed to eliminate such negativities, and to recommend a valuable industrial process.

Estimation of marginal excess moments for Weibull-type distributions

We consider the estimation of the marginal excess moment (MEM), which is defined for a random vector (X, Y) and a parameter β>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta >0$$\\end{document} as E[(X-QX(1-p))+β|Y>QY(1-p)]\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathbb {E}[(X-Q_{X}(1-p))_{+}^{\\beta }|Y> Q_{Y}(1-p)]$$\\end{document} provided E|X|β<∞\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathbb {E}|X|^{\\beta }< \\infty $$\\end{document}, and where y+:=max(0,y)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$y_{+}:=\\max (0,y)$$\\end{document}, QX\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q_{X}$$\\end{document} and QY\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q_{Y}$$\\end{document} are the quantile functions of X and Y respectively, and p∈(0,1)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\in (0,1)$$\\end{document}. Our interest is in the situation where the random variable X is of Weibull-type while the distribution of Y is kept general, the extreme dependence structure of (X, Y) converges to that of a bivariate extreme value distribution, and we let p↓0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p \\downarrow 0$$\\end{document} as the sample size n→∞\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n \\rightarrow \\infty $$\\end{document}. By using extreme value arguments we introduce an estimator for the marginal excess moment and we derive its limiting distribution. The finite sample properties of the proposed estimator are evaluated with a simulation study and the practical applicability is illustrated on a dataset of wave heights and wind speeds.

Measurements of Thermoelectric Properties of Identical Bi-Sb Sample in Magnetic Fields and Influence of Sample Geometry

Measurements of Thermoelectric Properties of Identical Bi-Sb Sample in Magnetic Fields and Influence of Sample Geometry

Characterization of wood plastic composites made with recycled waste tire rubber

Abstract Green materials are currently demanded for construction as well as other products since the 26th UN Climate Change Conference of the Parties (COP26) in 2021. Using renewable and sustainable resources to innovate new materials such as composites is encouraged. This study aimed to investigate the physical and mechanical characteristics of wood plastic composites (WPCs) when adding waste tire rubber as filler for 10% or 20% by weight. The results showed that the density of the WPC samples (50 wt% wood − 50 wt% high density polyethylene) increased with the addition of the waste tire rubber (WTR) while the dimensional stability of samples was reduced. The mechanical properties of the WPC samples were determined, including flexural strength, flexural modulus, elongation at break, tensile strength, tensile modulus, and impact strength. The WTR as filler in the WPC tended to decrease the tensile strength and flexural strength whereas it improved the impact strength of materials. The results indicated that the WTR as recycled material in WPC affected the physical and mechanical properties of the WPCs. Although the use of the WTR in the production of the WPC adversely affects the mechanical properties, the use of 10 wt% WTR was acceptable. The results of the study showed that the addition of the WTR to the WPC production process can be useful for its recycling and for reducing the cost of the WPC.

Sugar profile and sensory properties of honey from different geographical zones and botanical origins in Tanzania

Honey composition and sensory properties depend greatly on its botanical and geographical origins. In this study, the sugar profile and sensory properties of honey samples from different geographical zones and botanical origins in Tanzania were investigated. Thirty-two samples (3 zones x 2 origins x 4 samples) + (2 zones × 1 origin x 4 samples) were collected from the seven regions in five zones as follows; Simiyu (lake zone), Tabora and Dodoma (central zone), Manyara (northern zone), Morogoro (eastern zone), and Kigoma and Katavi (western zone) and evaluated for sugar profile and sensory properties using standards methods. Honey samples were primarily composed of fructose (39.5–47 g/100 g), glucose (32.0–35.0 g/100 g) and a small amount of sucrose (5.1 ± 0.50–7.3 ± 0.7 g/100 g). The total sugar ranged from 72.6 to 75.8 g/100 g/100g. The variations in sugar contents between zones and botanical origin were significant (p < 0.05) except for glucose. Sample from miombo origin in the lake and eastern zones had the highest fructose value (41.9 ± 0.8–42.04 ± 4.34 g/100 g) compared to lowest values (39.5 ± 2.17 g/100g) in a western zone while northern and lake zones had significantly (p < 0.05) highest and lowest sucrose values respectively. In all zones, acacia samples had higher fructose and sucrose contents than their miombo counterparts. As for the sensory profile, miombo samples in the western zone had significantly (p < 0.05) higher colour (8.0 ± 0.64) and aroma (7.5 ± 1.09) intensities while the lake zone samples had higher clarity (6.9 ± 1.76) than other zones’ samples. The findings have demonstrated that the geographical and botanical origins have a significant impact on the sugar profile and sensory profile of Tanzania honey. However, despite the variations, the consumption of honey from these zones and origins should be encouraged in light of their nutritional and related known health benefits.

Cheddar cheese production, structure and in-vitro semi-dynamic gastric digestion: The role of β-casein phenotype

The objective of this study was to establish the impact of β-casein A1/A1, A1/A2 and A2/A2 phenotypes on the cheese-making process, cheese structure and on the subsequent in vitro gastric digestion properties of the cheese samples. The time required for curd cutting in cheese milk containing β-casein A2/A2 was significantly delayed, compared to milks containing β-caseins A1/A1 and A1/A2. After 180 days of ripening no differences were observed in the level of soluble nitrogen at pH 4.6 between any of the cheese samples, with a decrease in the level of aggregated β-sheets and increase in the level of β-turns and random coils observed in all cheese over the ripening period. During simulated gastric digestion, cheese samples took between 15 and 20 min to form the initial digesta coagulum, which occurred between pH 4.3 and 4.0. The rate of protein breakdown was slower in A2/A2 cheese, with less cheese structure degradation occurring, compared to β-casein A1 containing cheeses. This study has shown that rennet coagulation takes significantly longer in cheese milk containing only β-casein A2/A2, and that there was less protein breakdown during its simulated gastric digestion.